wich and Harwell. The results are shown in Fig. 6 together with the cumulative Sr*” fallout in
rain at Milford Haven, reported by Stewart et al. (1956).
7
CUMULATIVE TOTAL
5°99 FALLOUT
6 F-
x SR
da
o
—sH6
oO
2
=
z
—47
—
45
2
a
4-—
—42
=
oO
oO
=
os
=
=
43a
wo 3-—
yu
wo
a
4
2 -—
LAB
ye
+
0
SYMBOL
HARWELL
WOOLWICH
NEW YORK
1954
|
t
4955
1956
|
+
oO
x
—42
2
_I,
0
1957
Fig. 6—Sr*™in Somerset milk.
A comparison of the milk activity with the total fallout shows that, whereas the latter has
increased fairly steadily for the pa * three years, the former rose quickly from about 2 to 5
S.U. in the spring of 1955 and has thereafter stayed fairly constant. The median of thirteen
1956 samples is 4.4 S.U., compared with 4.1 S.U. in 1955. The general trend is consistent with
the theory that the milk activity is determined partly by the cumulative fallout and partly by the
rate of fallout.
In October and again in December 1956, samples of dried milk from various parts of Britain
were obtained, and Sr®™ and Sr®° determinations made, with results shown in Table 5. There is
Table 5—-REGIONAL COMPARISON OF Sr*® AND Sr®* IN DRIED MILK
Date of
Sr,
Sr?o
SrBt
Ratio
Area
manufacture, 1956
pe/e Ca
puc/g Ca
ppe/g Ca
Sr® /gr®
Carmarthen
Carmarthen
Yorkshire
Oct. 17
Dec. 29
Oct. 16
200
8.0
7.2
4.3
190
30
53
23
4.2
12
Yorkshire
Cumberland
Cumberland
Antrim
Dec.
Oct.
Dec.
Oct.
3.9
6.5
5.6
6.9
19
100
5
150
4.8
15
0.8
22
Antrim
27
19
25
19
240
410
Londonderry
Oct. 17
Dec. 28
270
Londonderry
Somerset
Somerset
Dec. 27
Oct. 26
Dec. 28
280
230
7.0
24
3.4
10.3
220
21
6.2
4.6
5.5
22
110
25
3.6
24
4.5
a tendency in both sampling periods for the Sr*° activity to be higher in milk from the North and
West of the British Isles than in that from the South and East. This is probably an effect of
rainfall amounts. The activity of just over 10 S.U. found in the October sample from Londonderry, Northern Ireland compares with maxima of 10 S.U. or slightly more, reported from
218